It is desirable to control the temperature of a bed or other piece of furniture that supports a person, such as when sleeping. Such control has therapeutic value in treating symptoms of menopause or conditions of hypothermia or hyperthermia, particularly when those conditions manifest themselves over a long period of time. Therapeutic value may also be seen for individuals who have circulatory disorders, sleep disorders, and other conditions that may be improved by increasing the comfort felt during sleep. Such control can be desirable even outside the therapeutic value of cooling or heating a mattress, simply to match the personal comfort preferences of healthy individuals, or to provide localized control when a more general control, such as heating or air conditioning of a sleeping space, is unavailable or when adjustments to the general control would cause others discomfort or would be inefficient from an energy consumption perspective.
Various methods of temperature control are known, including such classic systems as electric blankets or heating pads, as well as more recent developments that involve the circulation of a heated or cooled fluid through a mattress, such as directing air through the chambers of an air mattress or directing air or a fluid through a tube that is embedded within a mattress or a mattress topper. The more advanced of these systems utilize a heat source or sink (i.e., cooling source) to heat or cool a reservoir of fluid to a selected target temperature and pump the heated or cooled fluid through the available conduit, relying on principles of heat exchange to control the mattress temperature.
In connection with the known methods of accomplishing temperature control, there are various problems and deficiencies that render these known methods ineffective or less than fully effective at achieving temperature control under optimal conditions. For example, such systems, particularly those that are designed for cooling, can be fairly noisy, thereby interfering with the subject individual's ability to sleep and defeating many of the therapeutic aspects of such systems.
Of somewhat more universal importance, however, is the lack of specificity such systems have in controlling temperatures in various zones of coverage, when the user desires different temperatures in different zones. A user that desires a particular temperature for sleeping may share his or her bed with another person who desires a different temperature for sleeping—a situation that may lead to arguments, one user's lack of comfort, or a compromise that leaves neither partner happy. Another user may desire, for example, a certain temperature for the majority of his or her body but a somewhat warmer temperature for his or her feet, or a somewhat cooler temperature for his or her head.
In order to satisfy the need for multiple zones, conventional systems have heretofore utilized multiple apparatuses to conduct zone-independent temperature modulations. In the situation where the bed is to be shared, each side of the bed may be provided with its own independent temperature control apparatus. A similar arrangement could potentially be used for different zones associated with a single user. However, conventional arrangements that require multiple independent systems require substantial duplication of the most expensive and potentially noisy parts of a conventional temperature control system—the circulation pump and the heating or cooling source.
Yet another issue with conventional single-zone systems is that they are not programmatically controllable over time. Although some systems provide for thermostatic control to prevent overheating or overcooling, some users may desire, for example, a warmer temperature at bedtime and a cooler temperature later in the sleep cycle, or vice versa. These systems are even more deficient when the user wishes to coordinate varying temperatures in various zones with various stages of the sleep cycle in order to promote deeper and more satisfying sleep.
Although many of the applications of the present invention relate to sleep and beds, the invention is equally applicable to other types of support furniture, such as chairs, or to more portable systems, such as wheelchair cushions, blankets, or mattress toppers.
What is needed is a multi-zone temperature modulation system that enables selective and independent heating or cooling of specific zones using a single heating or cooling apparatus and pump to minimize the cost efficiency of manufacture, and that may be programmatically controlled to vary the target temperature over time according to personal comfort or sleep cycle considerations.